1. Field of the Invention
This invention relates to pumps and, more particularly, to centrifugal pumps capable of continuous elevation of massive flows of fluids to higher elevations.
2. Description of the Prior Art
In the realm of industrial equipment, pumps are indispensable. They are used to raise water from wells, move gases and fluids through pipelines, compress gases, create partial vacuums, pressurize fluids, and for countless other uses.
There are two basic kinds of pumps: mechanical and non-mechanical. Mechanical pumps, which are the most common type, rely on moving parts to generate the pumping action. Non-mechanical, on the other hand, move fluids by means of either electromagnetic force or the force of another fluid such as compressed air.
Most mechanical pumps are driven by a rotational power source, such as an electric motor, an internal combustion engine, a steam engine, a turbine engine, or a windmill.
Pumps are typically rated by the pressure that they can generate and the volume of fluid which they can deliver per unit of time. Certain types of pumps can deliver up to 2,650,000 liters (700,000 gallons) per minute, while other types of pumps can generate pressures up to 14,000 kg/cm2 (200,000 lbs/in2).
Many different types of mechanical pumps are available. Reciprocating pumps, which provide a discontinuous, or pulsating, supply of fluid, generally employ either a single-acting or double acting piston. The most common types of rotary pumps are gear pumps and sliding vane pumps. The former generally has a pair of meshed gears that are rotated inside an oblong chamber. Fluid is carried in spaces between the teeth of the gears and the walls of the chamber, thereby creating a partial vacuum at the inlet and drawing in addition fluid. Sliding vane pumps employ a rotor that is eccentrically mounted within a circular chamber so that it almost touches the chamber at a line parallel to the axis of rotation. Vanes, installed in slots evenly spaced about the circumference of the rotor, are generally pressed against the circular wall by centripetal force. As the rotor turns, fluid is carried in the cavities formed by the vanes and the wall of the chamber from one side of the chamber to the other. The off-center mounting of the rotor prevents backflow of fluid. Centrifugal pumps, which generally provide high rates of flow at moderate pressures, have an impeller with multiple curved blades mounted within a generally circular chamber having an axial intake and a rim outlet. As the impeller spins, the blades throw the fluid toward the rim, creating a partial vacuum near the impeller axle. Axial flow pumps have a bladed impeller mounted axially within a cylinder. As the impeller spins, the blades on the impeller cause fluid inside the cylinder to flow parallel to the impeller's axis of rotation. Mixed flow pumps combine the operating features of centrifugal and axial-flow pumps.